Process for controlling the torque of an internal combustion engine

Abstract

In a process for controlling the torque of an internal combustion engine, an automatic gear system driven by the internal combustion engine includes a gear control device (1) and the internal combustion engine has a control device which, based on speed, load and, where appropriate, temperature signals, controls an ignition angle of an ignition system and/or an injection pulse width of a fuel injection system. The gear control device (1), for its part, controls on the basis of speed and load requirement signals the gear changes of the automatic gear. To improve the control of the whole drive unit, for the purpose of reducing fuel consumption and having smooth gear changes, the computer systems of the gear control drive (1) and of the control (2) of the internal combustion engine constantly intercommunicate via interfaces (3), the control device (2) of the internal combustion engine receiving from the gear control (1), in a cyclic time beat, a percentage torque requirement (PLF) on the basis of which the control device (2) automatically influences the torque of the internal combustion engine.

We claim: 
     
       1. A method for controlling torque of an internal combustion engine arranged to provide driving power to a motor vehicle via an automatic gear system, said internal combustion engine including an engine control device (2) which, based upon at least speed and load signals received from said internal combustion engine, controlling at least one of an ignition angle of an ignition system and an injection pulse width of a fuel injection system, the automatic gear system having a gear system control device (1) which, based on received speed and load requirement signals, controlling gear changes of the automatic gear system, and a computer system of said gear system control device (1) and a computer system of said engine control device (2) constantly communicating with one another via interfaces (3), wherein said engine control device (2) periodically receives from said gear system control device (1), a percentage torque requirement (PLF) based on which said engine control device (2) automatically influences the torque of the internal combustion engine; said method comprising the steps of: detecting with said gear system control device (1) when a change of torque occurs;   varying the percentage torque requirement (PLF) sent via said interface (3) in accordance with a gradient (d PLF ); and   determining said gradient (d PLF ), as a function of a set end value of a torque requirement (PLF2), a variable factor of the torque requirement (PLF) and a load signal, as follows: d PLF  =f (PLF2, PLF, load).   
     
     
       2. A method according to claim 1, further comprising the step of, during a change in torque produced by a gear change, generating a variable factor (PLF) of the torque requirement upon one of commencing engagement and commencing disengagement of friction elements participating in a gear change. 
     
     
       3. A method according to claim 1, further comprising the step of, for each variation of a final set value (PLF2) of the torque requirement, computing a final set value (PLF2), for a specific mode of travel, from a variable factor (PLF) minus a product of the variable factor and a weighing factor (Fak(T)) which is a function of a load requirement and speed (n 1 , n 2 ), that is: PLF2=PLF-PLF×Fak (T) , wherein Fak (T)=f (n 1 , n 2  load). 
     
     
       4. A method according to claim 1, further comprising the step of detecting, with said gear system control device (1), reduced torque requirements which occur as a result of slippage in wheels of the motor vehicle. 
     
     
       5. A method according to claim 2, further comprising the step of, during an overlap in which two friction elements are engaged and result in an increased torque requirement (PLF2), briefly peaking the torque of the internal combustion engine so that a reduction in an output torque (T ab ), occurring during such overlap, is compensated. 
     
     
       6. A method according to claim 5, further comprising the step of briefly increasing the torque of the internal combustion engine to a value above a maximum torque value (100%) by changing the injection pulse width of the fuel injection system. 
     
     
       7. A method according to claim 1, further comprising the step of detecting, with said gear system control device (1), the percentage torque requirement (PLF) as a first variable and a clutch pressure (p K ) of shifting elements, as a second variable, and, based upon the first and second variables (PLF, p K ), influencing an output torque (T ab ) of the gear system and grinding periods (T S ) of the shift elements independently of one another. 
     
     
       8. A method according to claim 1, further comprising the step of using a temperature of the internal combustion engine as an input to control the torque of the internal combustion engine.